The present exemplary embodiment relates generally to techniques for measuring a response to actuation of an electro-mechanical transducer in a print head assembly for an inkjet printing system. It finds particular application in methods and measurement devices for measuring the response of the transducer based on monitoring signals in the ground path of the transducer. However, it is to be appreciated that the exemplary embodiments described herein are also amenable to using recordings of the response signal in conjunction with subsequent operational or diagnostic testing of the transducer, print head assembly, or other components of the inkjet printing system.
Piezo element self-sensing is a method used in an inkjet printing system to gather information on the performance of ejectors in an inkjet print head. The technique involves recording drive/response signals from the actuation piezo elements in response to fluidic pressure waves immediately after the electrical signal that drives the piezo to eject a droplet. This technique was originally patented in the United States by Océ N. V. of The Netherlands (see, e.g., U.S. Pat. Nos. 6,682,162; 6,910,751; 6,926,388; 7,357,474; 7,488,062; and 7,703,893). The Océ patents describe the technique and various ways to either implement it or determine ejector characteristics. A similar technique was patented in the United States by Samsung (see, e.g., U.S. Pat. No. 7,866,781). The Samsung patent uses a differential configuration on the drive voltage coupled to a fixed capacitor that is matched to the capacitance of the piezo actuator.